December 2019 Outlook

December 2019 Outlook

Written on 12/01/2019
Jonathan Carr

It’s time to harness WeatherTrends360 technology and look at how December 2019 should play out. WeatherTrends360 algorithms are documented with an 84% verification rate and are based on oceanic water cycles, time table series and very complex mathematics. The best takeaway from this data are general trends (cool vs warm, rainy vs dry, etc). I’m always hesitant to forecast specific surface conditions (rainfall amounts, snowfall amounts, winds, etc) beyond the 7 -day forecasting period. But temperature and precipitation trends are what WeatherTrends360 does best with their proprietary mathematical analysis derived from over 150 years of reactive pattern data. For this reason, let’s call this a long-range discussion of reasonable expectations rather than a locked-in long-range forecast.


The following diagram is calculated using WeatherTrends360 proprietary algorithms for New Jersey in general. Please keep in mind that micro-climate influences can vary. NWNJ elevations, SENJ Pine Barrens and immediate coastal areas, for example, will verify slightly cooler than illustrated due to elevation, soil and marine flow influence. Interior CNJ/SNJ (closer to N Delaware/Philly/Trenton – I-95 corridor) slightly warmer than illustrated due to urban heat island effect and several other influencing factors. All areas of NJ however would have similar graph trends and sky conditions. It’s best to let the graph paint an overall picture (trends) instead of focusing on the low-level details.

Discussion: Meteorological winter starts today and we have a wintry storm about to impact at least NNJ and some parts of CNJ. Most of SNJ will escape the wintry impacts from this system. I’ll have a full update on Monday Dec 2 snow expectations at 5pm today (Sun Dec 1).

Sea surface temperatures up and down the ocean-facing NJ coast are between upper-40s and lower-50s. They are dropping as expected but have a long way to go before bottoming out in the upper-30s in February. With that said most of SNJ/SENJ/ECNJ do not see a lot of snowfall this time of year especially when coastal lows generate onshore flow. You need a thread the needle storm for it to happen. It has happened before but statistics over time say it is rare. NNJ (NW of the I-95/NJTP corridor) is favored for wintry impacts this time of year via climatology. It’s only after Christmas time that all parts of NJ are game for synoptic snowfall. We’re not far away.

Moving forward (after the Dec 2 snow event) we are looking at a very volatile period between about Dec 6-12. As the above graph indicates we bottom out cold Dec 6-8 then spike warm Dec 9-12. After that things moderate towards average to slightly below-average temperatures overall for December. It is reasonable to assume that the volatile Dec 6-12 period could see some synoptic precipitation. Obviously there should be some powerful fronts shifting cold and warm air masses around. Let’s call it an overall storm signal regardless of precipitation types. It takes decent synoptic energy to change temperature around that much so something should be cooking.

With all of that said I think we are going to see a period of above-average temperatures in the second week of December followed by slightly below-average temperatures to close the month. Certainly cold enough for any snow storms that form but not the shivering Arctic blast kind of cold. You know I’ll be watching.


In English: December starts with a snow/rain (NNJ/SNJ) storm and stays cold until about Dec 9. Dec 9-12 then looks mild with temperatures returning to near/slightly below-average for the rest of the month. Precipitation looks near-average for the month of December. These are the general expectations for the month. Any specific synoptic storm signals will be handled within the traditional 7-day forecasting period. Have a great December and please be safe! JC